关键词: 精密单点定位, 随机模型, 对流层天顶延迟, 非线性最小二乘估计, 全球定位系统

Abstract:

The GPS-measured tropospheric zenith path delay(ZPD) plays a key role in atmospheric sciences, the numerical weather forecasting, and so on. Differential GPS technology is widely used in GPS-measured ZPD, but this technology has some drawbacks, such as inefficiency, high cost and low removability. However, undifferenced GPS does not suffer from these drawbacks. The tropospheric zenith path delay in Shanghai is measured by precise point positioning (PPP) and a new stochastic model using the satellite elevation angle-based cosine function. The quality of the PPP-derived ZPD is examined through comparison with two independent datasets: nearby radiosonde records and the estimation by GIPSY. It is found that the PPP-derived ZPD agrees well with results of GIPSY and radiosonde, with the Root Mean Square Error (RMS) value and mean bias being in the range of centimeter level. Consequently, it is feasible to measure the tropospheric zenith path delay by a singular ground-based undifferenced GPS and PPP's accuracy is nearly equal to the accuracy of GIPSY.

Key words: precise point positioning, stochastic model, tropospheric zenith path delay, nonlinear least-squares estimation, global positioning system